David Smith,
In our phone conversation of March 3, you discussed Stuart Keeler's contribution to developing circle-grid analysis.
In my stint at Twinsburg Stamping, I would see stampings made from circle gridded sheet. These would frequently be on a check fixture. I never witnessed any analysis of the circle grids.
The March 2006 issue of MetalForming contains an ad identifying the product that FMTI Systems, Inc. of Hamilton, Ontario will display at MetalForm, the Model 100U Grid Analyzer.
This is used to measure strain in sheetmetal with circle and square grids. The shoot-and-measure process increases accuracy to 0.5 percent engineering strain, plots the points on the forming limit diagram, and generates a report page. Datapoints and images may be exported and used with other programs to generate reports. Other features include polka-dot and tick-tack-toe grids, multi-operation strain analysis and forming-limit curve generation.
This leaves me with a couple of questions. To achieve reproducible results, I would expect that actual production blanks would be printed with circle grid. How is that done? Is the circle grid damaged by the 1475ºF temperature at which Hot-stamped Boron steel and other new steels are formed?
James G Peck
jamesgpeck@yahoo.com
